package com.hj.saapp.common.utils;

public class Base64 {

  private static final byte[] encodingTable = { (byte) 'A', (byte) 'B',
          (byte) 'C', (byte) 'D', (byte) 'E', (byte) 'F', (byte) 'G',
          (byte) 'H', (byte) 'I', (byte) 'J', (byte) 'K', (byte) 'L',
          (byte) 'M', (byte) 'N', (byte) 'O', (byte) 'P', (byte) 'Q',
          (byte) 'R', (byte) 'S', (byte) 'T', (byte) 'U', (byte) 'V',
          (byte) 'W', (byte) 'X', (byte) 'Y', (byte) 'Z', (byte) 'a',
          (byte) 'b', (byte) 'c', (byte) 'd', (byte) 'e', (byte) 'f',
          (byte) 'g', (byte) 'h', (byte) 'i', (byte) 'j', (byte) 'k',
          (byte) 'l', (byte) 'm', (byte) 'n', (byte) 'o', (byte) 'p',
          (byte) 'q', (byte) 'r', (byte) 's', (byte) 't', (byte) 'u',
          (byte) 'v', (byte) 'w', (byte) 'x', (byte) 'y', (byte) 'z',
          (byte) '0', (byte) '1', (byte) '2', (byte) '3', (byte) '4',
          (byte) '5', (byte) '6', (byte) '7', (byte) '8', (byte) '9',
          (byte) '+', (byte) '/' };
  private static final byte[] decodingTable;
  static {
    decodingTable = new byte[128];
    for (int i = 0; i < 128; i++) {
      decodingTable[i] = (byte) -1;
    }
    for (int i = 'A'; i <= 'Z'; i++) {
      decodingTable[i] = (byte) (i - 'A');
    }
    for (int i = 'a'; i <= 'z'; i++) {
      decodingTable[i] = (byte) (i - 'a' + 26);
    }
    for (int i = '0'; i <= '9'; i++) {
      decodingTable[i] = (byte) (i - '0' + 52);
    }
    decodingTable['+'] = 62;
    decodingTable['/'] = 63;
  }
  public static byte[] encode(byte[] data) {
    byte[] bytes;
    int modulus = data.length % 3;
    if (modulus == 0) {
      bytes = new byte[(4 * data.length) / 3];
    } else {
      bytes = new byte[4 * ((data.length / 3) + 1)];
    }
    int dataLength = (data.length - modulus);
    int a1;
    int a2;
    int a3;
    for (int i = 0, j = 0; i < dataLength; i += 3, j += 4) {
      a1 = data[i] & 0xff;
      a2 = data[i + 1] & 0xff;
      a3 = data[i + 2] & 0xff;
      bytes[j] = encodingTable[(a1 >>> 2) & 0x3f];
      bytes[j + 1] = encodingTable[((a1 << 4) | (a2 >>> 4)) & 0x3f];
      bytes[j + 2] = encodingTable[((a2 << 2) | (a3 >>> 6)) & 0x3f];
      bytes[j + 3] = encodingTable[a3 & 0x3f];
    }
    int b1;
    int b2;
    int b3;
    int d1;
    int d2;
    switch (modulus) {
      case 0: /* nothing left to do */
        break;
      case 1:
        d1 = data[data.length - 1] & 0xff;
        b1 = (d1 >>> 2) & 0x3f;
        b2 = (d1 << 4) & 0x3f;
        bytes[bytes.length - 4] = encodingTable[b1];
        bytes[bytes.length - 3] = encodingTable[b2];
        bytes[bytes.length - 2] = (byte) '=';
        bytes[bytes.length - 1] = (byte) '=';
        break;
      case 2:
        d1 = data[data.length - 2] & 0xff;
        d2 = data[data.length - 1] & 0xff;
        b1 = (d1 >>> 2) & 0x3f;
        b2 = ((d1 << 4) | (d2 >>> 4)) & 0x3f;
        b3 = (d2 << 2) & 0x3f;
        bytes[bytes.length - 4] = encodingTable[b1];
        bytes[bytes.length - 3] = encodingTable[b2];
        bytes[bytes.length - 2] = encodingTable[b3];
        bytes[bytes.length - 1] = (byte) '=';
        break;
    }
    return bytes;
  }
  public static byte[] decode(byte[] data) {
    byte[] bytes;
    byte b1;
    byte b2;
    byte b3;
    byte b4;
    data = discardNonBase64Bytes(data);
    if (data[data.length - 2] == '=') {
      bytes = new byte[(((data.length / 4) - 1) * 3) + 1];
    } else if (data[data.length - 1] == '=') {
      bytes = new byte[(((data.length / 4) - 1) * 3) + 2];
    } else {
      bytes = new byte[((data.length / 4) * 3)];
    }
    for (int i = 0, j = 0; i < (data.length - 4); i += 4, j += 3) {
      b1 = decodingTable[data[i]];
      b2 = decodingTable[data[i + 1]];
      b3 = decodingTable[data[i + 2]];
      b4 = decodingTable[data[i + 3]];
      bytes[j] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2));
      bytes[j + 2] = (byte) ((b3 << 6) | b4);
    }
    if (data[data.length - 2] == '=') {
      b1 = decodingTable[data[data.length - 4]];
      b2 = decodingTable[data[data.length - 3]];
      bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4));
    } else if (data[data.length - 1] == '=') {
      b1 = decodingTable[data[data.length - 4]];
      b2 = decodingTable[data[data.length - 3]];
      b3 = decodingTable[data[data.length - 2]];
      bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2));
    } else {
      b1 = decodingTable[data[data.length - 4]];
      b2 = decodingTable[data[data.length - 3]];
      b3 = decodingTable[data[data.length - 2]];
      b4 = decodingTable[data[data.length - 1]];
      bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2));
      bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4);
    }
    return bytes;
  }
  public static byte[] decode(String data) {
    byte[] bytes;
    byte b1;
    byte b2;
    byte b3;
    byte b4;
    data = discardNonBase64Chars(data);
    if (data.charAt(data.length() - 2) == '=') {
      bytes = new byte[(((data.length() / 4) - 1) * 3) + 1];
    } else if (data.charAt(data.length() - 1) == '=') {
      bytes = new byte[(((data.length() / 4) - 1) * 3) + 2];
    } else {
      bytes = new byte[((data.length() / 4) * 3)];
    }
    for (int i = 0, j = 0; i < (data.length() - 4); i += 4, j += 3) {
      b1 = decodingTable[data.charAt(i)];
      b2 = decodingTable[data.charAt(i + 1)];
      b3 = decodingTable[data.charAt(i + 2)];
      b4 = decodingTable[data.charAt(i + 3)];
      bytes[j] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[j + 1] = (byte) ((b2 << 4) | (b3 >> 2));
      bytes[j + 2] = (byte) ((b3 << 6) | b4);
    }
    if (data.charAt(data.length() - 2) == '=') {
      b1 = decodingTable[data.charAt(data.length() - 4)];
      b2 = decodingTable[data.charAt(data.length() - 3)];
      bytes[bytes.length - 1] = (byte) ((b1 << 2) | (b2 >> 4));
    } else if (data.charAt(data.length() - 1) == '=') {
      b1 = decodingTable[data.charAt(data.length() - 4)];
      b2 = decodingTable[data.charAt(data.length() - 3)];
      b3 = decodingTable[data.charAt(data.length() - 2)];
      bytes[bytes.length - 2] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[bytes.length - 1] = (byte) ((b2 << 4) | (b3 >> 2));
    } else {
      b1 = decodingTable[data.charAt(data.length() - 4)];
      b2 = decodingTable[data.charAt(data.length() - 3)];
      b3 = decodingTable[data.charAt(data.length() - 2)];
      b4 = decodingTable[data.charAt(data.length() - 1)];
      bytes[bytes.length - 3] = (byte) ((b1 << 2) | (b2 >> 4));
      bytes[bytes.length - 2] = (byte) ((b2 << 4) | (b3 >> 2));
      bytes[bytes.length - 1] = (byte) ((b3 << 6) | b4);
    }
    return bytes;
  }
  private static byte[] discardNonBase64Bytes(byte[] data) {
    byte[] temp = new byte[data.length];
    int bytesCopied = 0;
    for (int i = 0; i < data.length; i++) {
      if (isValidBase64Byte(data[i])) {
        temp[bytesCopied++] = data[i];
      }
    }
    byte[] newData = new byte[bytesCopied];
    System.arraycopy(temp, 0, newData, 0, bytesCopied);
    return newData;
  }
  private static String discardNonBase64Chars(String data) {
    StringBuffer sb = new StringBuffer();
    int length = data.length();
    for (int i = 0; i < length; i++) {
      if (isValidBase64Byte((byte) (data.charAt(i)))) {
        sb.append(data.charAt(i));
      }
    }
    return sb.toString();
  }
  private static boolean isValidBase64Byte(byte b) {
    if (b == '=') {
      return true;
    } else if ((b < 0) || (b >= 128)) {
      return false;
    } else if (decodingTable[b] == -1) {
      return false;
    }
    return true;
  }
}